skysight-inc/HackerNews huggingface dataset:
Arena allocation is feasible only for particular types of allocation patterns. If that weren't true, every malloc() implementation would just be based on an arena allocator.

Specifically, for arena allocation to work, you have to have points at which you know all objects in an arena will become garbage. There are many situations where you know that most objects will quickly become garbage (say 98%), but can only guarantee at a very large scope that all objects will become garbage.

Consider something like a compiler that optimizes a tree by replacing sets of nodes with simpler ones. Where do you put the pool delete operation? You know lots of nodes will become garbage after each optimization pass, but you know some will survive. But you can't statically segregate which ones. So you can put the pool delete at the very end after code generation, when you know you don't need the tree anymore. But then your memory use skyrockets--you don't reclaim any memory until the very end of the process.

GCC, for example, used to use a pool allocation functionality called obstack's. They ended up switching to a home-rolled GC because it became too hard to manage that system.
I very very much doubt you'd just make something up. I'm just saying there are alternate explanations that make more sense. Happy to be wrong; still stand by my analysis. :)
Even more handy would be to submit a pull request! It's open source! https://github.com/jdm/asknot
Not the main point, but I just checked and have Xcode 4.5.1 running on an early 2007 MacBook. So about 5.5 years old.

Of course that still means a MacBook is needed, just not a recent one.
I am not sure you are right about young developers versus 'old' enterprise developers. (for the sake of argument, i am not thinking that way)

To actually success replacing SAP, for instance, you must support legacy applications, old modules, and various minor modifications for tiny little features demanded 10 years ago which nobody really knows why needed in the first place.

Startups tend to go for the 'easy'/'cool', 'brilliant' new idea and not for the boring, tedious huge applications, simply because it's faster to build new ideas.

Take a look at the open source operating system community for instance. There is no real big 'new' development there, and neither in the compilers, debuggers and C runtime libraries. No one wants to rewrite it. It simply work. There are two major compilers (correct me if I am wrong) in the open source community and no one writes a full scale compiler simply because he has new idea about how to generate code faster.

It is somewhat the same in the enterprise area. People like to do easy work, that's all.
To many people, Ubuntu represents nothing but a shiny front end build on top of the years of hard work spent on building Debian, the universal OS.

These people (we) are willing to use Ubuntu, since it is pretty much the same thing, but they (we) will never go out and actively support the Ubuntu project as we believe that Debian is more deserving of our support.
Its definitely not 100% accurate. We can calculate observables like mass from basic principles to +/- 2-3%. However, there are a few things they didn't mention.

First, these things are not simulated at anything approaching realtime. Things are simulated on timescales almost as vanishingly small as the space-scales, and even this takes hours on some of the largest research clusters.

Second, these aren't simulations in the sense that you're used to. They involve taking a volume in 4-space (3x space and 1x time) and using Monte Carlo techniques to approximate what happens in that space-time. It is non-trivial to pick up where (in time) one calculation left off and start a new one, and would introduce a lot of error.

Third, the calculation time doesn't scale with the volume (or even the 4-space volume). Naively, it scales with volume squared.* We actually do somewhat better than this right now, but again, approximations are required to get there.

*Its actually the number of points in the lattice squared, so increasing accuracy by decreasing the space between sites scales as you'd expect.

Source: I spent more time than I care to admit writing a very simple version of these simulators as an undergrad.
Stock price plummeting below asset value indicates that investors believe that Zynga is now in the business of burning money instead of making money.
RainRoom Lets You Experience Rainfall While Staying Dry
Did you not notice that removing the branch also sped up the Java code considerably? Also, there's potentially more speed in the Java code than reported given that warm-up time for hotspot is probably included in the reported numbers.

You present this as a difference between C and 'higher level languages' but a C programmer who didn't know anything about branch prediction would have no more or less chance to fix this issue as a Java programmer with the same lack of knowledge. So, this is an issue of programmer knowledge and not anything to do with the programming language.

I'm sick of hearing stuff like this repeated by people who clearly have no experience of optimising code in each of C, C++ and Java.
>If you think Ubuntu provides you with $X in value but you literally do not have $X to your name, well, I'm not sure how it could be providing $X to you, then.

I'm not sure I follow your reasoning.

Imagine I have disposable income of $0 and I currently use Ubuntu. By your reasoning, Ubuntu is worthless to me. However, let's say that if you offered me $1 to stop using Ubuntu, I would say say "no". We can safely conclude that Ubuntu is worth more than $1 to me, even though I don't have $1 to pay for it.

Ability to pay doesn't always equal value created. If I like take walks in a national park, I obviously derive value from that resource, but I don't pay anything for it and it doesn't allow me to generate any additional income.
Nit-picking at what must be the atomic level considering the depth and detail of this perfectly brilliant reply.

Can't have it both ways. The more depth and detail a discussion tries to present, the more important it is to get the details right. The medium (StackExchange) even recognizes this and has editing, correcting, and collaborative fixing built into its DNA, for that very reason.

The more famous this response becomes, the more ESL readers there will be. Why trip them up this way? There's just no reason to use "fail" like this here.

"Branch prediction fail" is not actually a very clear or precise phrase. It could mean the failure of a single branch prediction attempt; it could mean the failure of the technique in a particular case, and it could refer to an author's opinion that it was a failure in general. Why muddy the waters?
Do you mean why, or how?

As to "why", equity values are often more about emotion than reality (sometimes much more). Sometimes people want to bail from a stock that's become unpopular, and they don't bother to notice that the stock valuation is lower than the value of the buildings and inventory.

As to "how", there's nothing to stop a market valuation from being lower than the most basic assessment of the physical value of a company's assets, separate from present and future business prospects.

The single most important thing to remember about equities is that decisions need to be based to some extent on how stockholders think and behave, not necessarily on what makes sense. A person could on principle hold onto a stock in a company whose assets are very valuable, only to watch the stock drop to $0.01 per share, based on mass psychology rather than common sense.
Isn't that exactly what I said? Note that "destroy memory parallelism" is often not a high penalty in typical workloads where all in-flight accesses are hitting L1 cache only. It's not nearly as high as the "full round trip to DRAM" latency implied by calling it a "lock".
The answer focuses on branch misprediction but there is also another factor - CPU data prefetch.

In order to offset increasing CAS latencies (largely due to the increasing number of channels) modern CPU's are greedy (in a good sense) and fetch more pages per memory controller read request than are necessary.

If your data is laid out continuously (in this case - sorted), chances of the pages you need next being primed via prefetch are greatly increased and further read requests to the memory controller may be reduced or avoided.

I benchmarked the effect of data prefetching on modern processors with large data structures (usually limited to L1d cache lines):

https://github.com/johnj/llds#l1-data-prefetch-misses-200000...

A plausible analogy for CPU prefetching would be "readahead" mechanisms implemented by modern filesystems and operating systems.
Libgdx on iOS - First blood
Agree with this so much. So many people view Getting Things Done as an infomercially, buzzwordy system when it's really just a set of "best practices" for everyday thinking. You can consider it and take away whatever works for you, and it's almost guaranteed that you'll find at least one thing that improves the way you think and work every day.

In contrast, Jeff's advice is the only way he found to work effectively and, he reasons, the only way anyone in a similar profession can work effectively. In reality, you may think that having next action lists and reviews are "productivity porn" and wasted time, while others may think that they help keep your mind clear and focused. You're going to do that work of evaluating priorities and deciding what to work on anyway, so there's no harm in being honest about it, isolating it, and minimizing the context switches. There's also no harm in going Jeff's route and doing "lazy evaluation" on that meta-work, only deciding when you need to. We all think and remember differently, so the debate will never truly end.

Personally, I'm in favor of advocating the best hacks and systems that people have found, preferably with grains of salt and low buzzword count, and letting people figure out what works best for them. As coders, we're used to the luxury of strong opinions and relatively hard evidence, but that's not something that will happen here.
Didn't they try to ease stock away from those who owned it pre-IPO? How has that panned out now? … Was it converted to less valuable cash at the time, or is the cash more valuable now? (or was it that they got nothing in exchange for losing the stock)
We can make the penalties for any real problems that arise as strong as needed... when they arise. Expulsion from Uber/etc might be enough. If it isn't, it doesn't require traditional licensing/regulation to increase the penalties for specific actions.
Hmm... Perhaps we should crowd source Nasa
I believe that those who cared about company values did see this coming. See this one comment in Hacker News about a year ago: http://news.ycombinator.com/item?id=3225688
XAMPP(Apache, PHP, MySQL and Perl)= works on cloud Linux servers.
www.noti-fi.com. Need help.
Chrome Security Contest Pwnium 2 Results
Show HN: Launch-Soon, a Heroku-ready open source LaunchRock-type site
Your definition made me stop and think about how big of an asshole I really am. It is tough to somehow relate and try and measure it, because I reason a lot of social interactions and judge them as logical entities. Like you said not all assholes arent that bad, because not all of them realize they are assholes.

Though your term used to define it is wonderful. I would major in asshology if given the chance. But it would require a minor in chraminology. :)
Just Fucking Sell: Part 2
Well, obviously cheating is bad. And obviously breaking an ethics code is bad. I think an issue with what's going on here is that, in this case, there are conflicting natures between education and programming.

To be a good programmer, you need to be efficient. Writing 100% unique code is not efficient. It's not even good. It's bad. Good developers research solutions to solved problems. Good solutions have been used and tested by dozens, if not hundreds, of other developers in just as many different use-cases.

So, as a DEVELOPER, it's GOOD to research and find an existing solution to your problem. It's even good to go on places like Stack Overflow and post your problem and let someone else solve it for you.

But, as a STUDENT, doing these things is BAD. Taking credit for someone else's work isn't good. And letting other people do your work for you is cheating.

So, how do you resolve being a STUDENT DEVELOPER? Do you follow practices that would make you a bad developer? Or do you follow practices that would make you a bad student?

What I see is a complication in proving that the student understands the concepts they need to understand for the course. If you just go out and copy other people's code, but never take the time to understand it, then the course is worthless. Remember that the knowledge and understanding gained is the purpose of the course. Assignments, quizzes, whatever - these are just measurement tools, they are not the purpose behind the course.

I feel that we probably just need a different way to determine whether or not a student understands the concepts of the course. Is there a way to determine a student's understanding or comprehension outside of assignments, tests, and quizzes? Something that isn't replicable student to student?
I agree. If you can't remember, it's not a priority for you and that's okay. I operate the same way and have "hectic" schedules too.
Another Must-Watch Movies List (#2)
Microsoft patents 180 y.o. mapping technique
Don't forget to enable GPU Acceleration too. I've posted about this here: http://codebutler.com/2012/10/10/configuring-a-usable-androi...
In that case, wouldn't the 200x200px square with the anomaly still be highlighted as unique from the rest of the sand, since none of the sand would match it?
Is it just me, or are these flashy new Blogger themes not really that impressive? This is what the official Gmail blog looks like on my (android) phone:

https://plus.google.com/112865255606805639625/posts/8E8Mtx9f...
Obama gets sudden spike in Facebook 'likes'
"call her"??? Atwood never "calls her"! She calls Atwood! Hey and I don't mean in the Hollywood kind of way - Atwood Da Man!!!
Because the market doesn't have any faith the company will do anything good with the cash.
You don't have to change the subject to be about my capacity for imagination, or some bias you perceive in other HN conversations.

There aren't 10 such companies now. There might never be. Nor is there yet any evidence of consumer harm.

Imagining the worst when it might never materialize is a bad basis for policy. Especially with all the new factors which provide stronger, more-immediate checks on bad-actors: many of which apply to one operator or 100 equally well.

Why not give them a chance to work before constraining new operators to an ancient system which (a) disappointed customers with scarcity; and (b) got captured by incumbents?
Any developer with a moderate amount of common sense who chose to work for Zynga should've seen this coming. Zynga has been criticized for its business model and the way it treats its employees for a long time now.
The PayPal donation page says Canonical Ltd, so it looks like it's not the Ubuntu Foundation that's taking the money.
I used Debian stable as my primary OS for a couple of years. While I was just fine without the fancy desktop, at the time Firefox was stuck on version 3.0 even though 3.6 was available.

I don't know what the situation is like now, since I haven't used linux on my laptop for a couple years, but if I were to go back, I would want something like Debian stable, but with an updated browser.
The lack of relationship syncing is particularly irksome when using Siri.
dm-cache: new caching method that operates within the Linux kernel
This reminds me of a Portland Community College professor that repeatedly stated (in a blog post on women in engineering) that he expected the females in his class to do far worse in his courses than her male peers because he believed women's brains weren't capable of such high-level thinking. When you have this type of mindset on both sides of the fence, it's no wonder we have so many discussions on why more women aren't involved in these fields.
Now there's a bright mind with (possibly) a more-than-good job offer.
Additional info: https://www.cloudvps.com/blog/cloudvps-activates-linux-ssd-c...
when i saw this i really was hoping that the project would have some ~$50 option where you could buy the plans to assemble the desk out of 2x4s and support general development of some fancier option. (hi din0bot!)
The point isn't that AirBnB is better or worse for finding a renter than Craigslist or an ad in the local paper. The point is that renters create more risk than owners, and short-term renters create more risk than long-term renters.

If you own a house in the middle of the woods, you bear all the risk for the quality of your renter. If you live in a condo building, the other tenants are exposed to that risk. In the former case, I can totally control the level of risk I'm exposed to based on my choices of who I host. In the latter case, if I'm a fellow tenant, I have no control over that risk. The AirBnB host in my building might only choose tenants with 100+ reviews, or they may choose tenants with no reviews.
40% of US teens have an iPhone
Kickstarter Officially Expands to the U.K.
Zynga stock is trading 9.6% below book value.
While I have never worked there, I think the assumption pre-IPO was that yes you might get abused but it will all be worth it in the end because of the equity - remember Zynga according to tech blogs was the hottest thing coming out of the oven a couple years ago.

This also isn't all that unusual of an attitude in a hyped startup - management will abuse you (ahem, I mean expose you to a dynamic exciting work environment) and you will take it because your going to be rich in a few years... or not.
They control their cash and assets. This indicates that investors believe Zynga will use up their assets without producing any profit from them—that is, their RoE is negative.
Aren't Google Tasks synced through Google Calendar as events?
You would be paying less than book value (value of copmany divided by number of shares), true.

However, if they lose money, then the book value will drop some more. Only if the company failed utterly and then returned the money to the shareholders (not likely) would it be "safe" to focus on book value.
Hoosiers to get the world's fastest academic super computer
If I were implementing this for NASA, I'd run the analysis a number of times using different patches for my samples. Any areas that come up as anomalies more than once are probably worth checking out.

You can choose patches randomly, but they probably also have good enough telemetry and modeling to be able to predict which areas in any given picture are going to show part of the rover. That data can be used to ensure that your random patches don't include rover parts.
New startup fundraising rules will cause fraud, abuse, 'chaos' —critics
So when do the corporate raiders come to perform a hostile takeover and liquidate Zynga for the cash and real estate?
I did nothing of the sort.
So just ship the new one instead.
Finally got an emulator running :-D

"Start quickly." - not today, but hopefully in the future?

"Run smoothly." - ehmmm... Nope! Smooth as barbed wire...

"Are lightweight." - perhaps, but that makes little difference if it fails the first two bullet points.

Fantastic idea - had it worked. Let's hope it will with some tweaking :-)
Somewhere his boss is wondering what on earth that guy was doing all day.

Yet, he has demonstrated to a wide audience what good image processing and lateral thinking can do, he has brushed up on a few parts of mathematica he has not used this past quarter and the world is a little bit richer

A TED talk recently mentioned how robots are replacing us and we need to manage a jobless future - this indicates how we might do it.

Plus, I cannot work out which is worse - that bits of metal are dropping off the Rover. Or not ...
Teenage Hacker Hacks Chrome
How about Canonical pays me for the hours I've spent debugging problems like scripts shipped with bugs or complete changes to the foundations of the operating system which just appear by surprise?

I really like it when motd just randomly became some convoluted set of scripts.
Also keep in mind that learning to "organize your data for fetching" is not necessarily something you can do before you start your project. Many (most?) times you can't predict which data access patterns will be most common and benefit from using Redis, etc.

Starting with a "slower, but flexible" datastore like a traditional relational database, monitoring which access patterns need a boost, and then optimizing or introducing a new datastore is almost always a solid plan of attack.
Google the ip, thats how I tracked down a hacker that hacked into my previous work computers. But I think the Google maps location tip by mouseroot is very good.
> Sometimes I wonder how old 'news' can be and still climb up to the top of HN. Is there somewhere a search engine which can tell the author if something was on HN already?

What value is there to the people who are finding this content interesting today in rejecting it because some other subset of the HN community saw it at some arbitrarily distant time in the past?

Reposted interesting technical content beats the hell out of Boring industry naval-gazing news story #82795 and Android vs Apple "news" intended to provoke a fanbo flamewar thread #762483101.

If you're spending so much time on HN that you not only recognize reposts but that you see them so often it bothers you enough to complain in the comments, consider doing something more productive with your time.
This is totally missing the point of a major part of HN's (and other communities') value: The actual links may or may not be important, it's the community discussion that has the more value. In many cases, I find myself not even clicking on the links on HN (either the topic is too mundane or I've already seen it from another source) but go straight for comments.

This particular post is a good example: I have seen this interesting SO tidbit before but learned a few things from the HN discussion.
Want to make some money? Do it for me.
Good point, thanks for correcting me. Can you give a hint how this would raise the computational cost?
I'm not really disagreeing with you, but I think we're using the terminology differently. To me, "memory" is the whole memory pipeline--everything from the load/store units, through the load/store buffers, the caches, to DRAM.

When I said it was a "locked memory transaction of some sort" I was including the effect of a serializing instruction which prevents concurrent load/store operations even if they hit the cache. I wasn't trying to imply a full round trip to DRAM.
Should FB buy them? Much of Zynga's trouble has been that their interests and Facebook's didn't align.

My first thought was "Why bother? FB can just wait and pick up the good staff in the wind down." But the exact opposite of that logic has led to acquihires.
I would not be so sure - they will have a lot of image processing but they are not sending back realtime video - they only have limited bandwidth so the number of images is fairly low. I would guess NASA spotted it pretty similarly to how the rest ofus did - suddenly going wtf is that?
trainenquiry.com is operated by CRIS (which falls under the railways ministry). So they have access to all of IR data.
Warmer until the bed-desk doesn't come through and they're out $650 :)
While I agree with this statement somewhat, I can't imagine the talented devs at Zynga didn't have common sense. Seems harsh to write those people off with essentially 'you only have yourselves to blame'. That attitude also removes some of the responsibility from the folks at the top.
Maybe Canonical should add an option on that screen to donate to Debian?
Technology Will Replace 80% of Doctors